The present invention concerns a method of draining a system for anchoring a structural cable to a construction element.
The structural cable in question may be a stay, a suspension cable or a prestressing cable.
It is routine for the structural cables usually encountered to comprise a plurality of strands each of which includes metal wires themselves wrapped together in a protective sheath. Each of these protective sheaths is interrupted at the level of a terminal end so that the strands each have a stripped end section.
The anchoring systems usually encountered include:                a perforated anchor block to which are individually anchored the stripped end section or sections of the cable,        a bearing surface that is fixed with respect to the construction element and against which the perimeter of the perforated block bears axially,        one or more chambers containing stripped parts of the structural cable (possibly divided into strands) together with a filling material. There is generally a first chamber situated on the side of the anchor block from which the structural cable arrives and inside which the protective sheaths are interrupted.        
The filling material is generally a petroleum wax or a grease. It is injected hot into the chamber or chambers of the anchorage after fitting the cable and anchoring it. After cooling, it forms a solid or a thick paste that adheres to the stripped cable and provides the required seal.
Now it may prove useful to change the filling material, either during construction because it has not been injected correctly, or during the service life of the construction work, during maintenance operations on the anchor system. For some chambers of the anchor system, this does not give rise to any problem. For example, for a chamber located under a cap and containing the end part of the structural cable that emerges from the anchor block, the filling material may be removed with the aid of a trowel and/or a flow of hot air.
At present, there is no method for draining some chambers of the anchor system to which access is difficult, for example a chamber situated behind the anchor block, in a part of the anchor system buried in the construction work.
An object of the present invention is to solve some or all of the problems referred to above, that is to say in particular to provide a method for draining an anchor system of a structural cable including a chamber filled with a filling material to which access is difficult.